Operation with bandwidth-limited devices in a wireless network

ABSTRACT

A first communication device allocates respective portions of a communication channel, that includes at least one primary component channel and one or more non-primary component channels, to a plurality of second communication devices, including a bandwidth-limited second communication device configured to operate with a maximum bandwidth that is less than a full bandwidth of the communication channel. The bandwidth-limited second communication device is operating in a particular component channel, and allocation of a frequency portion to the bandwidth-limited second communication device is restricted to the particular component channel. The first communication device transmits a data unit that includes one or both of: respective data for the second communication devices in the respective frequency portions allocated to the respective second communication devices, and one or more trigger frames to prompt transmission of respective data by the second communication devices in the respective frequency portions allocated to the respective second communication devices.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/262,355, entitled “OPERATION WITH BANDWIDTH-LIMITED DEVICES IN AWIRELESS NETWORK,” filed on Jan. 30, 2019, which claims the benefit ofU.S. Provisional Patent App. No. 62/624,642, entitled “HE 20 MHZ ONLYDEVICES IN 5 GHZ BAND,” filed on Jan. 31, 2018. The disclosures of bothapplications identified above are hereby expressly incorporated hereinby reference in their entireties.

FIELD OF TECHNOLOGY

The present disclosure relates generally to wireless communicationsystems, and more particularly wireless communication devices reportingbandwidth capabilities to other communication devices.

BACKGROUND

Wireless local area networks (WLANs) have evolved rapidly over the pastdecade, and development of WLAN standards such as the Institute forElectrical and Electronics Engineers (IEEE) 802.11 Standard family hasimproved single-user peak data throughput. For example, the IEEE 802.11bStandard specifies a single-user peak throughput of 11 megabits persecond (Mbps), the IEEE 802.11a and 802.11g Standards specify asingle-user peak throughput of 54 Mbps, the IEEE 802.11n Standardspecifies a single-user peak throughput of 600 Mbps, and the IEEE802.11ac Standard specifies a single-user peak throughput in thegigabits per second (Gbps) range. Future standards promise to provideeven greater throughput, such as throughputs in the tens of Gbps range.

SUMMARY

In an embodiment, a method involves communicating in a wireless localarea network (WLAN) that utilizes a communication channel having aplurality of component channels, the plurality of component channelsincluding i) at least one primary component channel in which an accesspoint transmits management frames including beacon frames, and ii) oneor more non-primary component channels. The method includes: receiving,at a bandwidth-limited client station that is configured to operate witha maximum bandwidth that is less than a full bandwidth of thecommunication channel, target wake time (TWT) information from theaccess point, the TWT information regarding a TWT period with the accesspoint and including an indication of a particular non-primary componentchannel among the one or more non-primary component channels in whichthe bandwidth-limited client station is expected to operate during theTWT period; switching operation of the bandwidth-limited client stationfrom one of the at least one primary component channels to theparticular non-primary component channel in connection with a start ofthe TWT period; operating the bandwidth-limited client station in theparticular non-primary component channel during the TWT period;receiving, at the bandwidth-limited client station during the TWTperiod, a data unit from the access point via the particular non-primarycomponent channel; and receiving, at the bandwidth-limited clientstation, a legacy packet from the access point in the particularnon-primary component channel, the legacy packet including a beaconframe.

In another embodiment, a wireless communication device is configured forcommunicating in a WLAN that utilizes a communication channel having aplurality of component channels, the plurality of component channelsincluding i) at least one primary component channel in which an accesspoint transmits management frames including beacon frames, and ii) oneor more non-primary component channels. The wireless communicationdevice comprises a wireless network interface device that is configuredto operate with a maximum bandwidth that is less than a full bandwidthof the communication channel. The wireless network interface devicecomprises one or more integrated circuit (IC) devices configured to:receive TWT information from the access point, the TWT informationregarding a TWT period with the access point and including an indicationof a particular non-primary component channel among the one or morenon-primary component channels in which the wireless communicationdevice is expected to operate during the TWT period; switch operation ofthe wireless network interface device from one of the at least oneprimary component channels to the particular non-primary componentchannel in connection with a start of the TWT period; operate thewireless network interface device in the particular non-primarycomponent channel during the TWT period; receive, during the TWT period,a data unit from the access point via the particular non-primarycomponent channel; and receive a legacy packet from the access point inthe particular non-primary component channel, the legacy packetincluding a beacon frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example wireless local area network(WLAN), according to an embodiment.

FIG. 2A is a block diagram of an example physical layer (PHY) data unit,according to an embodiment.

FIG. 2B is a block diagram of an example preamble of a PHY data unit,according to an embodiment.

FIG. 3 is a block diagram of an example data unit transmitted from anaccess point (AP) to a group of client stations that includes at leastone bandwidth-limited client station, according to an embodiment.

FIG. 4 is a block diagram of a communication exchange between an AP anda group of client stations that includes at least one bandwidth-limitedclient station, according to an embodiment.

FIG. 5 is a block diagram of another communication exchange between anAP and a group of client stations that includes at least onebandwidth-limited client station, according to another embodiment.

FIG. 6 is a block diagram of a scheduled communication session,according to an embodiment.

FIG. 7 is a block diagram of a procedure that a communication device isconfigured to implement to determine that one or more non-primarychannels of a communication channel are idle even if a primary channelof the communication channel is busy, according to an embodiment.

FIG. 8 is a block diagram of a procedure that a communication device isconfigured to implement to determine that one or more non-primarychannels of a communication channel are idle even if a primary channelof the communication channel is busy, according to another embodiment.

FIG. 9 is a flow diagram of an example method for operation of a firstcommunication device in a communication channel that includes multiplecomponent channels, according to an embodiment.

DETAILED DESCRIPTION

In embodiments described below, a first communication device (e.g., anAP) and one or more second communication devices (e.g., client stations)operate using a communication channel that includes a plurality ofcomponent channels, including a primary component channel and one ormore non-primary component channels. The one or more secondcommunication devices include a bandwidth-limited second communicationdevice that is capable of operating with at most a maximum bandwidththat is less than a full bandwidth of the communication channel. Forexample, in an embodiment, the bandwidth-limited second communicationdevice is capable of operating with a maximum bandwidth that correspondsto a bandwidth of only a single component channel of the communicationchannel. In an embodiment, the bandwidth-limited second communicationdevice is required to operate in a primary component channel of thecommunication channel. In another embodiment, the bandwidth-limitedsecond communication device is permitted to operate in any componentchannel of the communication channel, including a non-primary componentchannel. For example, the bandwidth-limited second communication devicemay operate in a particular non-primary component channel that may benegotiated between the first communication device and thebandwidth-limited second communication device, in an embodiment.

In an embodiment, when the bandwidth-limited second communication deviceis operating in a non-primary component channel of the communicationchannel, communications between the first communication device and thebandwidth-limited second communication device are restricted tocommunications included in multi-user transmissions (e.g., orthogonalfrequency division multiple access (OFDMA) transmissions) in whichrespective frequency portions of the communication channel are used forsimultaneous transmissions to or by a group of second communicationdevices. For multi-user transmissions, in an embodiment, the firstcommunication device allocates respective frequency portions of thecommunication channel to respective second communication devices in thegroup of second communication devices, and simultaneously transmitsrespective data to the second communication devices in the respectivefrequency portions allocated to the second communication devices and/orprompts transmission of respective data by the second communicationdevices in the respective frequency portions allocated to the secondcommunication devices. Generally, the first communication device mayallocate any frequency portion of the communication channel to anysecond communication device in the group of second communicationdevices, in an embodiment. However, when the group of secondcommunication device includes a bandwidth-limited second communicationdevice, the first communication device restricts allocation of afrequency portion to the bandwidth-limited second communication deviceto the particular component channel in which the bandwidth-limitedsecond communication device is operating, in an embodiment.

In at least some embodiments, restricting communication between thefirst communication device and the bandwidth-limited secondcommunication device to multi-user transmissions and also restrictingallocation of a frequency portion to the bandwidth-limited secondcommunication device to the particular component channel in which thesecond communication device is operating ensures that i) data of thebandwidth-limited second communication device is included in a frequencyportion in the particular component channel in which thebandwidth-limited second communication device is operating and ii)transmissions between the first communication device and thebandwidth-limited second communication device are included intransmissions that include the primary component channel, even if thebandwidth-limited second communication device is operating in anon-primary component channel. Because transmissions between the firstcommunication device and the bandwidth-limited second communicationdevice are included in transmissions that include the primary componentchannel even if the bandwidth-limited second communication device isoperating in a non-primary component channel, other communicationdevices that are monitoring the primary component channel are able todetermine that the communication channel is occupied based on detectingthe transmissions in the primary component channel and to refrain fromattempting to transmit in the communication channel, in an embodiment.

In some embodiments, a communication device (e.g., an AP or a clientstation) operating using a communication channel that includes aplurality of component channels is configured to perform channel accessprocedures, such as carrier sense and backoff procedures, in multipleones of the component channels. Performing channel access procedures inmultiple one of the component channels allows the communication deviceto transmit in one or more non-primary component channels that aredetermined to be idle even if a primary component channel is determinedto be busy, in an embodiment. Thus, for example, transmissions to or bya bandwidth-limited communication device that is operating in anon-primary component channel of the communication channel can occur inthe non-primary component channel even when the primary componentchannel of the communication channel is busy, in an embodiment.

Embodiments of methods and apparatus are described below in the contextof wireless local area networks (WLANs) that utilize protocols relatedto protocols defined by the 802.11 Standard from the Institute ofElectrical and Electronics Engineers (IEEE) merely for explanatorypurposes. In other embodiments, however, techniques for operation inwith bandwidth-limited communication devices are utilized in other typesof communication systems such as non-IEEE 802.11 WLANs, personal areanetworks (PANs), mobile communication networks such as cellularnetworks, metropolitan area networks (MANs), satellite communicationnetworks, etc.

FIG. 1 is a block diagram of an example wireless local area network(WLAN) 110, according to an embodiment. The WLAN 110 includes an accesspoint (AP) 114 that comprises a host processor 118 coupled to a networkinterface device 122. The network interface device 122 includes one ormore medium access control (MAC) processors 126 (sometimes referred toherein as “the MAC processor 126” for brevity) and one or more physicallayer (PHY) processors 130 (sometimes referred to herein as “the PHYprocessor 130” for brevity). The PHY processor 130 includes a pluralityof transceivers 134, and the transceivers 134 are coupled to a pluralityof antennas 138. Although three transceivers 134 and three antennas 138are illustrated in FIG. 1 , the AP 114 includes other suitable numbers(e.g., 1, 2, 4, 5, etc.) of transceivers 134 and antennas 138 in otherembodiments. In some embodiments, the AP 114 includes a higher number ofantennas 138 than transceivers 134, and antenna switching techniques areutilized.

The network interface device 122 is implemented using one or moreintegrated circuits (ICs) configured to operate as discussed below. Forexample, the MAC processor 126 may be implemented, at least partially,on a first IC, and the PHY processor 130 may be implemented, at leastpartially, on a second IC. As another example, at least a portion of theMAC processor 126 and at least a portion of the PHY processor 130 may beimplemented on a single IC. For instance, the network interface device122 may be implemented using a system on a chip (SoC), where the SoCincludes at least a portion of the MAC processor 126 and at least aportion of the PHY processor 130.

In an embodiment, the host processor 118 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a random access memory (RAM), a read-only memory (ROM), aflash memory, etc. In an embodiment, the host processor 118 may beimplemented, at least partially, on a first IC, and the network device122 may be implemented, at least partially, on a second IC. As anotherexample, the host processor 118 and at least a portion of the networkinterface device 122 may be implemented on a single IC.

In various embodiments, the MAC processor 126 and/or the PHY processor130 of the AP 114 are configured to generate data units, and processreceived data units, that conform to a WLAN communication protocol suchas a communication protocol conforming to the IEEE 802.11 Standard oranother suitable wireless communication protocol. For example, the MACprocessor 126 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 130 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. Forinstance, the MAC processor 126 may be configured to generate MAC layerdata units such as MAC service data units (MSDUs), MAC protocol dataunits (MPDUs), etc., and provide the MAC layer data units to the PHYprocessor 130. The PHY processor 130 may be configured to receive MAClayer data units from the MAC processor 126 and encapsulate the MAClayer data units to generate PHY data units such as PHY protocol dataunits (PPDUs) for transmission via the antennas 138. Similarly, the PHYprocessor 130 may be configured to receive PHY data units that werereceived via the antennas 138, and extract MAC layer data unitsencapsulated within the PHY data units. The PHY processor 130 mayprovide the extracted MAC layer data units to the MAC processor 126,which processes the MAC layer data units.

PHY data units are sometimes referred to herein as “packets,” and MAClayer data units are sometimes referred to herein as “frames.”

In connection with generating one or more radio frequency (RF) signalsfor transmission, the PHY processor 130 is configured to process (whichmay include modulating, filtering, etc.) data corresponding to a PPDU togenerate one or more digital baseband signals, and convert the digitalbaseband signal(s) to one or more analog baseband signals, according toan embodiment. Additionally, the PHY processor 130 is configured toupconvert the one or more analog baseband signals to one or more RFsignals for transmission via the one or more antennas 138.

In connection with receiving one or more signals RF signals, the PHYprocessor 130 is configured to downconvert the one or more RF signals toone or more analog baseband signals, and to convert the one or moreanalog baseband signals to one or more digital baseband signals. The PHYprocessor 130 is further configured to process (which may includedemodulating, filtering, etc.) the one or more digital baseband signalsto generate a PPDU.

The PHY processor 130 includes amplifiers (e.g., a low noise amplifier(LNA), a power amplifier, etc.), a radio frequency (RF) downconverter,an RF upconverter, a plurality of filters, one or more analog-to-digitalconverters (ADCs), one or more digital-to-analog converters (DACs), oneor more discrete Fourier transform (DFT) calculators (e.g., a fastFourier transform (FFT) calculator), one or more inverse discreteFourier transform (IDFT) calculators (e.g., an inverse fast Fouriertransform (IFFT) calculator), one or more modulators, one or moredemodulators, etc.

The PHY processor 130 is configured to generate one or more RF signalsthat are provided to the one or more antennas 138. The PHY processor 130is also configured to receive one or more RF signals from the one ormore antennas 138.

The MAC processor 126 is configured to control the PHY processor 130 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 130, andoptionally providing one or more control signals to the PHY processor130, according to some embodiments. In an embodiment, the MAC processor126 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a readROM, a flash memory, etc. In another embodiment, the MAC processor 126includes a hardware state machine.

In an embodiment, the MAC processor 126 and the PHY processor 130 areconfigured to operate according to a first WLAN communication protocol,and also according to one or more second WLAN communication protocols(e.g., as defined by one or more of the IEEE 802.11n Standard, IEEE802.11ac Standard, the IEEE 802.11ax Standard and/or other suitable WLANcommunication protocols) that are legacy protocols with respect to thefirst WLAN communication protocol. The one or more second WLANcommunication protocols are sometimes collectively referred to herein asa “legacy WLAN communication protocol” or simply “legacy protocol.”

The WLAN 110 includes a plurality of client stations 154. Although threeclient stations 154 are illustrated in FIG. 1 , the WLAN 110 includesother suitable numbers (e.g., 1, 2, 4, 5, 6, etc.) of client stations154 in various embodiments. The client station 154 includes a hostprocessor 158 coupled to a network interface device 162. The networkinterface device 162 includes one or more MAC processors 166 (sometimesreferred to herein as “the MAC processor 166” for brevity) and one ormore PHY processors 170 (sometimes referred to herein as “the PHYprocessor 170” for brevity). The PHY processor 170 includes a pluralityof transceivers 174, and the transceivers 174 are coupled to a pluralityof antennas 178. Although three transceivers 174 and three antennas 178are illustrated in FIG. 1 , the client station 154 includes othersuitable numbers (e.g., 1, 2, 4, 5, etc.) of transceivers 174 andantennas 178 in other embodiments. In some embodiments, the clientstation 154 includes a higher number of antennas 178 than transceivers174, and antenna switching techniques are utilized.

The network interface device 162 is implemented using one or more ICsconfigured to operate as discussed below. For example, the MAC processor166 may be implemented on at least a first IC, and the PHY processor 170may be implemented on at least a second IC. As another example, at leasta portion of the MAC processor 166 and at least a portion of the PHYprocessor 170 may be implemented on a single IC. For instance, thenetwork interface device 162 may be implemented using an SoC, where theSoC includes at least a portion of the MAC processor 166 and at least aportion of the PHY processor 170.

In an embodiment, the host processor 158 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a RAM, a ROM, a flash memory, etc. In an embodiment, thehost processor 158 may be implemented, at least partially, on a firstIC, and the network device 162 may be implemented, at least partially,on a second IC. As another example, the host processor 158 and at leasta portion of the network interface device 162 may be implemented on asingle IC.

In various embodiments, the MAC processor 166 and the PHY processor 170of the client device 154 are configured to generate data units, andprocess received data units, that conform to the WLAN communicationprotocol or another suitable communication protocol. For example, theMAC processor 166 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 170 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. The MACprocessor 166 may be configured to generate MAC layer data units such asMSDUs, MPDUs, etc., and provide the MAC layer data units to the PHYprocessor 170. The PHY processor 170 may be configured to receive MAClayer data units from the MAC processor 166 and encapsulate the MAClayer data units to generate PHY data units such as PPDUs fortransmission via the antennas 178. Similarly, the PHY processor 170 maybe configured to receive PHY data units that were received via theantennas 178, and extract MAC layer data units encapsulated within thePHY data units. The PHY processor 170 may provide the extracted MAClayer data units to the MAC processor 166, which processes the MAC layerdata units.

The PHY processor 170 is configured to downconvert one or more RFsignals received via the one or more antennas 178 to one or morebaseband analog signals, and convert the analog baseband signal(s) toone or more digital baseband signals, according to an embodiment. ThePHY processor 170 is further configured to process the one or moredigital baseband signals to demodulate the one or more digital basebandsignals and to generate a PPDU. The PHY processor 170 includesamplifiers (e.g., an LNA, a power amplifier, etc.), an RF downconverter,an RF upconverter, a plurality of filters, one or more ADCs, one or moreDACs, one or more DFT calculators (e.g., an FFT calculator), one or moreIDFT calculators (e.g., an IFFT calculator), one or more modulators, oneor more demodulators, etc.

The PHY processor 170 is configured to generate one or more RF signalsthat are provided to the one or more antennas 178. The PHY processor 170is also configured to receive one or more RF signals from the one ormore antennas 178.

The MAC processor 166 is configured to control the PHY processor 170 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 170, andoptionally providing one or more control signals to the PHY processor170, according to some embodiments. In an embodiment, the MAC processor166 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a ROM,a flash memory, etc. In an embodiment, the MAC processor 166 includes ahardware state machine.

In an embodiment, the MAC processor 166 and the PHY processor 170 areconfigured to operate according to the first WLAN communicationprotocol, and also according to the legacy WLAN communication protocol.

In an embodiment, each of the client stations 154-2 and 154-3 has astructure that is the same as or similar to the client station 154-1.Each of the client stations 154-2 and 154-3 has the same or a differentnumber of transceivers and antennas. For example, the client station154-2 and/or the client station 154-3 each have only two transceiversand two antennas (not shown), according to an embodiment.

In an embodiment, at least one client station 154 (e.g., the clientstation 154-3) is a bandwidth-limited client station that is configuredto operate with at most a maximum bandwidth that is less than a fullbandwidth of a communication channel used in the WLAN 110 forcommunication between the AP 114 and the client stations 154 (sometimereferred to herein as “a basic service set (BSS) operating channel” orsimply “communication channel”). For example, in an embodiment, thecommunication channel comprises a plurality of non-overlapping componentchannels, and a bandwidth-limited client station 154 is configured tooperate with a maximum bandwidth corresponding to a bandwidth of asingle component channel. According to one illustrative embodiment, thecommunication channel comprises multiple non-overlapping 20 MHzcomponent channels and has an overall bandwidth of 40 MHz, 80 MHz, 160MHz, etc., whereas the bandwidth-limited client station 154 isconfigured to operate with a maximum bandwidth of 20 MHz correspondingto a single 20 MHz component channel. For ease of explanation, abandwidth-limited client station is sometimes referred to herein as a“20 MHz-only” client station. In other embodiments, however, abandwidth-limited client station is configured to operate with asuitable maximum bandwidth other than 20 MHz (e.g., 1 MHz, 2 MHz, etc.).Similarly, a communication channel of the BSS supported by the AP 114has a suitable maximum bandwidth other than 40 MHz, 80 MHz, 160 MHz,etc. (e.g., 4 MHz, 8 MHz, 16 MHz, etc.), in some embodiments.

In an embodiment, the AP 114 and the client stations 154 are configuredfor multi-user (MU) communications that involve simultaneoustransmissions to or by multiple communication devices. For example, theAP 114 and the client stations 154 are configured for communicationsusing MU multiple input multiple output (MIMO) techniques in whichdifferent data streams are simultaneously transmitted to or by differentclient stations 154 via different spatial streams, according to someembodiments. As another example, the AP 114 and the client stations 154are configured for communications using OFDMA techniques in whichdifferent data streams are simultaneously transmitted to or by differentclient stations 154 in different frequency portions of a communicationchannel, according to some embodiments. In some embodiments, MU MIMOtechniques and OFDMA techniques are used during the same MUtransmission, e.g., to transmit some data streams via differentfrequency portions and to transmit some data streams via differentspatial streams within a same frequency portion. A downlink (DL) MUtransmission refers to an MU transmission from the AP 114 to multipleclient stations 154. An uplink (UL) MU transmission refers to an MUtransmission from multiple client stations 154 to the AP 114. In anembodiment, the AP 114 and the client stations 154 are additionallyconfigured for single user (SU) communications that involve transmissionto or by a single client station 154. A DL SU transmission refers to anSU transmission from the AP 114 to a single client station 154. A UL SUtransmission refers to an SU transmission from a single client station154 to the AP 114.

FIG. 2A is a diagram of an example PPDU 200 that the network interfacedevice 122 (FIG. 1 ) is configured to generate and transmit to one ormore client stations 154 (e.g., the client station 154-1 or a group ofclient stations that includes the client stations 154-1, 154-2 and154-3), according to an embodiment. The network interface device 162(FIG. 1 ) may also be configured to transmit data units the same as orsimilar to the PPDU 200 to the AP 114.

The PPDU 200 includes a PHY preamble 204 and a PHY data portion 208. ThePHY preamble 204 may include at least one of a legacy portion 212 and anon-legacy portion 216, in at least some embodiments. In an embodiment,the legacy portion 212 is configured to be processed by legacycommunication devices in the WLAN 110 (i.e., communication devices thatoperate according to a legacy communication protocol), enabling thelegacy communication devices to detect the PPDU 200 and to obtain PHYinformation corresponding to the PPDU 200, such as a duration of thePPDU 200.

FIG. 2B is a diagram of an example PHY preamble 220. In an embodiment,the PHY preamble 220 corresponds to the PHY preamble 204. In anembodiment, the PHY preamble 220 is included in the legacy portion 212.In another embodiment, the PHY preamble 220 is included in thenon-legacy portion 216. The PHY preamble 220 includes one or more shorttraining fields (STFs) 224, one or more long training field (LTFs) 228,and one or more signal fields (SIGs) 232. In an embodiment, the STFs 224and the LTFs 228 are used for packet detection, automatic gain control(AGC), frequency offset estimation, channel estimation, etc. In anembodiment, the number of LTFs in the LTFs 228 correspond to a number ofspatial/space-time streams used for transmission of the PPDU 200. In anembodiment, the SIGs 232 are used to signal PHY communication parameters(e.g., a modulation and coding scheme (MCS), a number of spatialstreams, a frequency bandwidth, etc.) corresponding to the PPDU 200.

In some embodiments, the PHY preamble 220 omits one or more of thefields 224-232. In some embodiments, the PHY preamble 220 includes oneor more additional fields not illustrated in FIG. 2B. In someembodiments, the order of the fields 224-232 is different thanillustrated in FIG. 2B. In an embodiment, the PPDU 200 is generated andtransmitted as a sequence of orthogonal frequency division multiplexing(OFDM) symbols. In an embodiment, each of the STF 224, the LTF 228, theSIG 232, and the data portion 208 comprises one or more OFDM symbols.

In an embodiment, the PPDU 200 has a 20 MHz bandwidth and is transmittedin a 20 MHz communication channel. In other embodiments, the PPDU 200has a suitable bandwidth different from 20 MHz and is transmitted in acommunication channel having a corresponding other suitable bandwidth.For example, in some embodiments, the PPDU 200 has a bandwidth of 40MHz, 80 MHz, 160 MHz, etc., and is correspondingly transmitted in a 40MHz, 80 MHz, 160 MHz, etc., communication channel, respectively. In somesuch embodiments, at least a portion of the PPDU 200 (e.g., at least alegacy portion of the PHY preamble 204, or the entirety of the PHYpreamble 204) is generated by generating a field corresponding to a 20MHz component channel of the communication channel and duplicating thefield over a number of 20 MHz channels corresponding all componentchannels of the communication channel. For example, in an embodiment inwhich the PPDU 200 occupies an 80 MHz communication channel, at leastthe legacy portion 212 corresponding to the 20 MHz component channelbandwidth is duplicated in each of four 20 MHz component channels thatcomprise the 80 MHz communication channel. In an embodiment, duplicationof at least a portion of the PPDU 200 duplicating the field over anumber of 20 MHz channels corresponding all component channels of thecommunication channel allows communication devices that are operating inonly a portion of the communication channel to obtain pertinentinformation, such as data unit duration information included in theduplicated portion of the PPDU 200, in any of the component channels ofthe communication channel. The communication device may utilize theobtained information to, for example, determine a length of time forwhich the communication channel is expected to be occupied in connectionwith transmission of the PPDU 200 and to refrain from attempting totransmit in the communication channel for the determined length of time,in an embodiment.

In an embodiment, the PPDU 200 is an MU OFDMA data unit in whichdifferent data streams are transmitted to or by multiple client stations154 using respective sets of OFDM tones allocated to the client stations154. For example, in an embodiment, available OFDM tones (e.g., OFDMtones that are not used as DC tone and/or guard tones) are segmentedinto multiple resource units (RUs), and each of the multiple RUs isallocated to one or more client stations 154. In an embodiment, the PPDU200 is an MU-MIMO PHY data unit in which different data streams aretransmitted to or by multiple client stations 154 using respectivespatial streams allocated to the client stations 154.

In an embodiment, the communication channel utilized for communicationsbetween the AP 114 and the client stations 154 includes a plurality ofcomponent channels including a primary component channel and one or morenon-primary component channels. A primary component channel is sometimesreferred to herein as simply “primary channel”, and a non-primarycomponent channel is sometimes referred to herein as simply “non-primarychannel” or “secondary channel.” The primary channel is utilized bycommunication devices (e.g., the AP 114 and client stations 154)operating for various operations. For example, the primary channel isutilized for various management transmissions (e.g., transmissionsassociated with association of a client station 154 with the AP 114,beacon transmissions by the AP 114, operating channel bandwidths switchannouncement transmissions, etc.), in an embodiment. As another example,the primary channel is utilized by the communication devices for channelaccess procedures, such as backoff procedures, clear channel assessment(CCA) procedures, carrier sensing procedures, etc., in an embodiment.

In an embodiment, a bandwidth-limited client station 154 is permitted tooperate only in a primary channel of the communication channel. As anexample, a 20 MHz-only client station 154 is permitted to operate onlyin a 20 MHz primary channel of the communication channel, in anembodiment. In another embodiment, a bandwidth-limited client station154 is permitted to operate in any component channel, including anon-primary component channel, of the communication channel. In anembodiment, the AP 114 and the bandwidth-limited client station 154 areconfigured to negotiate in which particular component channel of thecommunication channel the bandwidth-limited client station 154 will beoperating. For example, in an embodiment, after association of thebandwidth-limited client station 154 with the AP 114, which may occur inthe primary channel, a negotiation procedure is performed between thebandwidth-limited client station 154 and the AP 114 to negotiate inwhich component channel of the communication channel thebandwidth-limited client station 154 will be operating. Afternegotiation, the bandwidth-limited client station 154 switches from theprimary component channel to the negotiated non-primary componentchannel, in an embodiment.

In an embodiment, to allow client stations that are operating innon-primary component channels of the communication channel to receivemanagement frames in the non-primary channel, the AP 114 is configuredto transmit management frames, such as beacon frames, duplicated in eachcomponent channel of the communication channel. For example, in anembodiment, the AP 114 is configured to transmit management frames, suchas beacon frames, using duplicate legacy (e.g., non-HT) PPDU format. Inan embodiment, duplicate management frames are transmitted in eachcomponent channel of the communication channel, allowing communicationdevices, such as bandwidth-limited client stations 154, operating innon-primary component channels to receive the management frames in thenon-primary component channels. In some embodiments, transmission ofduplicate management frames is used for suitable purposes other than foroperation with bandwidth-limited client stations.

In an embodiment, SU transmissions and/or MU transmissions in thecommunication channel must include the primary channel of thecommunication channel. Thus, for example, SU transmissions to or by abandwidth-limited client station 154 that is operating in a non-primarychannel are not permitted, in an embodiment. That is, communicationsbetween the AP 114 and a bandwidth-limited client station 154 that isoperating in a non-primary channel are limited to MU communications, inan embodiment. Transmissions that include the primary channel allowcommunication devices that are not intended recipients of thetransmission to accurately set channel access parameters, such asnetwork allocation vectors (NAVs), based on detecting the transmissionin the primary channel and to refrain from attempting to transmit in thecommunication medium for the duration indicated in the transmission, inan embodiment. In other embodiments, however, SU transmissions and/or MUtransmissions that do not include the primary channel are permitted. Forexample, SU transmissions to or by a bandwidth-limited client station154 that is operating in a non-primary channel are permitted, in anembodiment.

In an embodiment, allocation of a frequency portion to abandwidth-limited client station 154 for MU communications, that includetransmissions to or by the bandwidth-limited client station 154, isrestricted to the particular component channel in which thebandwidth-limited client station 154 is operating. For example, if abandwidth-limited client station 154 is operating in the primarycomponent channel, such as in an embodiment in which bandwidth-limiteddevices are not permitted to operate in non-primary component channels,allocation of a frequency portion to the bandwidth-limited clientstation 154 is restricted to the primary component channel. On the otherhand, if a bandwidth-limited client station 154 is operating in aparticular non-primary component channel, such as a negotiatednon-primary component channel, allocation of a frequency portion to thebandwidth-limited client station 154 is restricted to the particularnon-primary component channel, in an embodiment.

FIG. 3 is a block diagram of an example DL OFDMA data unit 302transmitted from the AP 114 to a group of client stations 154 thatincludes at least one bandwidth-limited client station 154 (e.g., STA3),according to an embodiment. The DL OFDMA data unit 302 corresponds tothe data unit 200 of FIG. 2 , in an embodiment. The DL OFDMA data unit302 is a data unit different from the data unit 200 of FIG. 2 , inanother embodiment. The DL OFDMA data unit 302 includes respective dataunits 304 transmitted to respective client stations 154 in respectivefrequency portions (e.g., RUs) allocated to the client stations 154. Inan embodiment, allocation of a frequency portion to thebandwidth-limited client station 154 is restricted to a particularcomponent channel in which the bandwidth-limited client station 154 isoperating. The particular component channel in which thebandwidth-limited client station 154 may be a primary channel or may bea non-primary channel, in various embodiments. For example, in anembodiment in which bandwidth-limited client stations are required tooperate in the primary channel, allocation of a frequency portion to thebandwidth-limited client station 154 is restricted to the primarychannel. On the other hand, in an embodiment in which bandwidth-limitedclient stations are permitted to operate in non-primary channels and inwhich the bandwidth-limited client station 154 is operating in anon-primary channel (e.g., a previously negotiated non-primary channel),allocation of a frequency portion to the bandwidth-limited clientstation 154 is restricted to the non-primary channel in which the inwhich the bandwidth-limited client station 154 is operating, in anembodiment. Thus, for example, in an embodiment in which thebandwidth-limited client station 154 is operating in a non-primarycomponent channel, the AP 114 allocates to the bandwidth-limited clientstation 154 one or more RUs in the non-primary component channel. The AP114 also allocates any of the remaining available RUs to any of theother client stations 154 in the group. The AP 114 then generates the DLOFDMA data unit 302 such that data for respective client stations 154 isincluded in the RUs allocated to the respective client stations 154, inan embodiment. Thus, data for the bandwidth-limited client station 154is included in the DL OFDMA data unit 302 in the particular componentchannel in which the bandwidth-limited client station 154 is operating,allowing the bandwidth-limited client station 154 to receive its data inthe particular component channel in which the bandwidth-limited clientstation 154 is operating, in an embodiment.

FIG. 4 is a block diagram of a communication exchange 400 between the AP114 and a group of client stations 154 that includes at least onebandwidth-limited client station 154 (e.g., STA3), according to anembodiment. The communication exchange 400 includes a DL OFDMA data unit402 (e.g., DL PPDU). The DL OFDMA data unit 402 corresponds to the dataunit 200 of FIG. 2 , in an embodiment. The DL OFDMA data unit 402 is adata unit different from the data unit 200 of FIG. 2 , in anotherembodiment. Similar to the DL data unit 302 of FIG. 3 , the DL data unit402 includes respective DL data units 404 transmitted to respectiveclient stations 154 in respective frequency portions (e.g., RUs)allocated to the client stations 154. Additionally, the DL OFDMA dataunit 402 includes trigger frames 406 that include UL schedulinginformation to prompt the group of client stations 154 to transmit an ULOFDMA PHY data unit 410 (e.g., an UL OFDMA PPDU) a suitable time periodafter an end of the DL OFDMA data unit 402, in an embodiment. In anotherembodiment, the DL OFDMA data unit 402 includes UL schedulinginformation in formats other than a trigger frame format, such as, forexample, uplink response scheduling information, triggered responsescheduling information, etc. In response to receiving the trigger frames406 or UL scheduling information in another format, the client stations154 transmit respective UL data units 414 as parts of the UL OFDMA PHYdata unit 410 the suitable time period after the end of the DL OFDMAdata unit 402, in an embodiment.

In an embodiment, allocation of a frequency portion for transmission ofthe DL data unit 404 (e.g., the DL data unit 404-3) to thebandwidth-limited client station 154 is restricted to a particularcomponent channel in which the bandwidth-limited client station 154 isoperating. Similarly, allocation of a frequency portion for transmissionof the UL data unit 414 (e.g., the DL data unit 414-3) by thebandwidth-limited client station 154 is restricted to the particularcomponent channel in which the bandwidth-limited client station 154 isoperating, in an embodiment. In an embodiment, the AP 114 allocates tothe bandwidth-limited client station 154 a same frequency portion, inthe particular component channel in which the bandwidth-limited clientstation 154 is operating, for transmission of the DL data unit 404 tothe bandwidth-limited client station 154 and for transmission of the ULdata unit 414 by the bandwidth-limited client station 154. In anotherembodiment, the AP 114 allocates to the bandwidth-limited client station154 a same frequency portion, in the particular component channel inwhich the bandwidth-limited client station 154 is operating, a firstfrequency portion for transmission of the DL data unit 404 to thebandwidth-limited client station 154 and a second frequency fortransmission of the UL data unit 414 by the bandwidth-limited clientstation 154, where the second frequency portion is different (e.g.,includes one or more different RUs) than the first frequency portion.

The trigger frames 406 include user-specific allocation information toindicate to the respective client stations in the group of clientstations 154 particular frequency portions (e.g., RUs) that areallocated to the client stations 154 for transmission of the UL OFDMAPHY data unit 410, in an embodiment. The trigger frames 406 additionallyinclude other information, such as length or duration of the UL OFDMAPHY data unit 410, power level at which the UL OFDMA PHY data unit 410is to be transmitted, etc., in some embodiments. In an embodiment,different trigger frames 406 include different user-specific allocationinformation corresponding to different ones of the client stations 154.In an embodiment, user-specific allocation information corresponding tothe bandwidth-limited client station 154, and other parameters pertinentto transmission of the UL data unit 414 by the bandwidth-limited clientstation 154, are included in a trigger frame 406 (e.g., the triggerframe 406-3) that is transmitted in the particular component channel inwhich the bandwidth-limited client station 154 is operating. Forexample, in an embodiment, user-specific allocation informationcorresponding to the bandwidth-limited client station 154, and otherparameters pertinent to transmission of the UL data unit 414 by thebandwidth-limited client station 154, are included in a trigger frame406 (e.g., the trigger frame 406-3) that is included in the DL data unit404 that is transmitted to the bandwidth-limited client station 154 inthe particular component channel in which the bandwidth-limited clientstation 154 is operating. Including user-specific allocation informationcorresponding to the bandwidth-limited client station 154, and otherparameters pertinent to transmission of the UL data unit 414 by thebandwidth-limited client station 154, in a trigger frame that istransmitted in the particular component channel in which thebandwidth-limited client station 154 is operating ensures that thebandwidth-limited client station 154 will be able to receive and decodethe user-specific allocation information and the other parameterswithout receiving and decoding other frequency portions of the DL OFDMAdata unit 402, in an embodiment.

Respective client stations in the group of client stations 154 determinebased on information in the trigger frames 406 respective frequencyportions allocated to the client station 154 for uplink transmission tothe AP 114 and other parameters for the transmission uplink transmissionto the AP 114. The client stations 154 transmit, in the respectivefrequency portions allocated to the client stations 154, respective ULdata units 414 as parts of the UL OFDMA PHY data unit 410, in anembodiment.

FIG. 5 is a block diagram of a communication exchange 500 between the AP114 and a group of client stations 154 that includes at least onebandwidth-limited client station 154 (e.g. STA3), according to anotherembodiment. The communication exchange 500 includes a DL data unit 502(e.g., DL PPDU). The DL data unit 502 corresponds to the data unit 200of FIG. 2 , in an embodiment. The DL data unit 502 is a data unitdifferent from the data unit 200 of FIG. 2 , in another embodiment. TheDL data unit 502 includes trigger frames 506 to prompt the group ofclient stations 154 to transmit an UL OFDMA PHY data unit 510 (e.g., anUL OFDMA PPDU) a suitable time period after an end of the DL data unit502. Trigger frames 506 include user-specific allocation information toindicate to the respective client stations in the group of clientstations 154 particular frequency portions (e.g., RUs) that areallocated to the client stations 154 for transmission of the UL OFDMAPHY data unit 510, in an embodiment. The trigger frames 506 additionallyinclude other information, such as length or duration of the UL OFDMAPHY data unit 410, power level at which the UL OFDMA PHY data unit 510is to be transmitted, etc., in some embodiments.

In an embodiment, to allow the bandwidth-limited client station 154 toreceive and decode allocation information corresponding to thebandwidth-limited client station 154 in the particular component channelin which the bandwidth-limited client station 154 is operating, eachtrigger frame 506 includes allocation information for each of the clientstations 154 in the group. For example, in an embodiment, a duplicatemode (e.g., non-HT duplicate mode defined by the IEEE 802.11communication protocol) is used to transmit the DL data unit 502, wherea trigger frame is generated to include allocation information for eachof the client stations 154, and the trigger frame is duplicated fortransmission in each component channel, in an embodiment. In anembodiment, the bandwidth-limited client station 154 receives thetrigger frame 506 transmitted in the component channel in which thebandwidth-limited client station 154 is operating. Thus, for example, abandwidth-limited client station 154 that is operating in a non-primarycomponent channel receives the trigger frame 506 transmitted in thecorresponding non-primary component channel and, based on the triggerframe 506 received in the non-primary component channel, thebandwidth-limited client station 154 determines its allocationinformation and other parameters pertinent to transmission of its ULdata unit 514 as a part of the UL OFDMA data unit 510, in an embodiment.

In some embodiments, a bandwidth-limited client station 154 operates ina mixed mode in which the bandwidth-limited client station 154 switchesbetween operating in a non-primary component channel during some timesand operating in a primary component channel during other times. Forexample, in an embodiment, a non-primary component channel is negotiatedbetween a bandwidth-limited client station 154 and the AP 114 for useduring only some time scheduled periods, such as target wake time (TWT)scheduled periods (SP), and the bandwidth-limited client station 154switches to the non-primary component channel for operation during thescheduled time periods to a primary component channel for operationoutside of the scheduled time periods.

FIG. 6 is a diagram of a scheduled transmissions session 600 between theAP 114 and one or more client stations 154 including a bandwidth-limitedclient station 154, according to an embodiment. In an embodiment, thescheduled transmissions session 600 corresponds to a target wake time(TWT) session, and the scheduled transmissions session 600 is describedherein in the context of a TWT session and is sometimes referred toherein as a “TWT session” 600. In other embodiments, however, thescheduled transmissions session 600 is a suitable scheduled sessiondifferent from a TWT session. In an embodiment, the bandwidth-limitedclient station 154 transmits a TWT request data unit (e.g., MAC dataunit or frame) 602 to the AP 114. In response to receiving the TWTrequest data unit 600, the AP 114 transmits a TWT response data unit 604to the bandwidth-limited client station 154. The TWT request data unit602 and the TWT response data unit 604 are transmitted in the primarychannel of the communication channel, in an embodiment. The TWT requestdata unit 602 and the TWT response data unit 604 include respectiveinformation elements (e.g., TWT elements) to negotiate/indicateparameters of the TWT session 600, in an embodiment. The parametersnegotiated/indicated by the TWT request data unit 602 and the TWTresponse data unit 604 include i) a start time of a first TWT scheduledperiod (SP) 606-1 and ii) a TWT interval that defines times at whichsubsequent one or more TWT SP, such as a second TWT SP 606-2, during theTWT session 600 will occur, in an embodiment. The parametersnegotiated/indicated by the TWT request data unit 602 and the TWTresponse data unit 604 additionally include a particular componentchannel in which the bandwidth-limited client station 154 will beoperating during the one or more TWT SPs, in an embodiment.

In an embodiment, for operation during the TWT SPs 606, the clientstation switches to the particular component channel negotiated with theAP 114. Accordingly, during the TWT SPs 606, the AP 114 transmits dataunits to and/or receives data units from the bandwidth-limited clientstation 154 in the particular negotiated component channel, in anembodiment. For example, for MU communication with a group of clientstations 154 that includes the bandwidth-limited client station 154, theAP 114 restricts allocation of frequency portion(s) for transmission toor by the bandwidth-limited client station 154 to the particularnegotiated component channel. On the other hand, for operation duringthe time period(s) 608 of the TWT session 600, the bandwidth-limitedclient station 154 switches to the primary channel of the communicationchannel. Thus, in the time period(s) 608, transmissions to or by thebandwidth-limited client station 154, if any, occurs in the primarychannel, in an embodiment.

In an embodiment, the AP 114 and the client stations 154 contend for acommunication medium using CCA mechanisms, such as carrier sensemultiple access with collision avoidance (CSMA/CA) mechanism or anothersuitable channel assessment mechanism. In an embodiment, the AP 114 andthe client stations 154 maintain respective network allocation vectors(NAVs) that include timers for tracking when another communicationdevice has seized control or “ownership” of a wireless communicationmedium. For example, when a communication device (e.g., the AP 114 or aclient station 154) receives a transmitted PHY data unit (e.g., the PHYdata unit 200 of FIG. 2 or another suitable PHY data unit) that conformsto a particular communication protocol (e.g., the IEEE 802.11 Standard,a future version of the IEEE 802.11 Standard, or another suitablecommunication protocol), the communication device examines durationinformation included in a header or a preamble of the PHY data unit,where the duration information indicates a length of time that anothercommunication device has taken ownership of a communication medium. Thecommunication device then uses the duration information in the PHY dataunit to set a NAV timer, and the NAV timer begins to decrement. When avalue of the NAV timer is non-zero, this indicates that anothercommunication device owns the communication medium and that thecommunication device therefore should generally refrain fromtransmitting. On the other hand, when the value of the NAV timer reacheszero, this indicates that the communication medium is not currentlyowned by another communication device.

In an embodiment, when the NAV is zero, the communication deviceimplements a physical carrier sensing and energy detection procedure inwhich the communication device senses an energy level of the medium fora predetermined length of time, such as a length of time correspondingto a distributed coordination function (DCF) interframe space (DIFS)time period or another suitable time period, in an embodiment. Ifdetected energy in the medium during the predetermined length of timeremains below a threshold, then the communication device invokes abackoff procedure in which the communication device continues to detectenergy level of the medium, to determine whether medium is busy or idle,for an additional deferral time period. In an embodiment, the backoffprocedure includes randomly or pseudorandomly choosing an initial valuefor the backoff timer when the current value of the backoff timer iszero. In an embodiment, the communication device chooses the initialvalue for the backoff timer from a range of initial values [0, CW],where CW is a contention window parameter, where the initial value andCW are in units of slots, and where each slot corresponds to a suitabletime period. For example, the IEEE 802.11 Standard defines slot times of20 microseconds (IEEE 802.11b) and 9 microseconds (IEEE 802.11a, 11n,and 11ac), where different slot times are used for different versions ofthe protocol. In an embodiment, CW is initially set to a minimum valueCWmin. However, after each failed transmission attempt (e.g., failure toreceive an acknowledgment of the transmission), the value of CW isapproximately doubled with an upper bound of CWmax. The parameters CWminand CWmax are also in units of slots.

In an embodiment, while the communication device determines that themedium is idle, the communication device decrements the backoff timer.When the communication device determines that the communication mediumis busy, the communication device pauses the backoff timer and does notresume decrementing the backoff timer until the communication medium issubsequently determined to be idle. In an embodiment, setting thebackoff timer to an initial value chosen randomly or pseudo-randomly(e.g., as described above) ensures that backoff timers of differentcommunication devices in the network tend to reach zero at differenttimes. In an embodiment, when the backoff timer reaches zero, thecommunication device determines that the communication device is free totransmit.

Any suitable threshold energy level may be utilized. The thresholdenergy level for determining whether the medium is idle or busy may bedifferent depending on the bandwidth of the channel being used by thecommunication device and/or on whether the energy corresponds to atransmission that conforms to a wireless communication protocol,according to some embodiments. For example, in the communicationprotocol defined by the IEEE 802.11 Standard, if the channel bandwidthis 20 Megahertz (MHz), the threshold level is −82 decibel-milliwatts(dBm) for energy from transmissions that conform to the IEEE 802.11Standard (referred to as “valid 802.11” signals). For channel bandwidthsof 40 MHz, 80 MHz, and 160 MHz, the threshold levels are −79 dBm, −76dBm, and −73 dBm, respectively. For energy of signals not identified bythe communication device as a valid 802.11 signal, the threshold levelis −62 dBm, according to the IEEE 802.11 Standard.

In an embodiment, when a communication device (e.g., the AP 114 or aclient station 154) determines that a primary channel is idle based onCCA/backoff operations performed in the primary channel, thecommunication device also checks one or more non-primary channels todetermine whether the one or more non-primary channels can be utilizedfor transmission along with the primary channel. For example, in anembodiment, the communication device senses an energy levelcorresponding to the one or more non-primary channels for apredetermined length of time, such as a length of time corresponding topoint coordination function (PCF) interframe space (PIFS) time period,immediately preceding expiration of the backoff timer corresponding tothe primary channel. If detected energy level corresponding to one ormore of the non-primary channels is below a threshold, the communicationdevice determines that these one or more of the non-primary channels arealso idle. When the backoff timer reaches zero, the communication devicecan transmit in a composite channel that includes the primary channeland the one or more non-primary channels determined to be idle, in anembodiment, in an embodiment.

In various embodiments, a bandwidth-limited client station 154 performsclear channel assessment operations, for example to determine whetherthe bandwidth-limited client station 154 can respond to a trigger frame(e.g., the trigger frame 406 of FIG. 4 , the trigger frame 506 of FIG. 5or another suitable trigger frame) for uplink transmission or can itselfinitiate an uplink transmission, based on the particular componentchannel in which the bandwidth-limited client station 154 is operating.For example, when the bandwidth-limited client station 154 is operatingin the primary channel, the bandwidth-limited client station 154 setsits channel access timer (e.g., NAV) based on data units detected in theprimary channel, in an embodiment. Similarly, the bandwidth-limitedclient station 154 operating in the primary channel performs backoffoperations in the primary channel, in an embodiment. On the other hand,when the bandwidth-limited client station 154 is operating in anon-primary channel (e.g., a negotiated non-primary channel), thebandwidth-limited client station 154 sets its channel access timer(e.g., NAV) based on data units detected in the non-primary channel, inan embodiment. Similarly, the bandwidth-limited client station 154operating in the non-primary channel performs backoff operations in thenon-primary channel, in an embodiment.

In an embodiment, when a bandwidth-limited client station 154 switchesits operation to a new component channel (e.g., from a primary channelto a non-primary channel or vice versa) and prior to transmission in thenew component channel, the bandwidth-limited client station 154 performsclear channel assessment to determine whether the component channel isfree to transmit. In an embodiment, when switching to a new componentchannel, the bandwidth-limited client station 154 initially sets itschannel access timer (e.g., NAV) to a predetermined delay value, such asa NAVSYNCDELAY value. The bandwidth-limited client station 154 thenbegins to count down the channel access timer from the predetermineddelay value. If before the channel access timer reaches zero thebandwidth-limited client station 154 detects a PHY data unit in the newcomponent channel, the bandwidth-limited client station 154 resets thechannel access timer to a new value determined based on durationinformation in a header or preamble of the PHY data unit, and begins tocount down from the new value of the channel access timer. In any event,when the channel access timer reaches zero, the bandwidth-limited clientstation 154 performs a backoff operation corresponding to the newcomponent channel, and determines based on the backoff operation whetherthe new component channel is clear for transmission, in an embodiment.Thus, when switching to a new component channel, the bandwidth-limitedclient station 154 can begin backoff upon expiration of a predeterminedtime period (e.g., NAVSYNCDELAY) or, if the client station 154 detects aPHY data unit in the new component channel, upon expiration of a timeperiod corresponding to duration of the PHY data unit, in an embodiment.

In an embodiment, during a time period when a bandwidth-limited clientstation 154 is switching channels, such as switching from a primarycomponent channel to a non-primary component channel or vice versa, thebandwidth-limited client station 154 is operating in power save mode.For example, prior to switching channels, the bandwidth-limited clientstation 154 informs the AP 114 that the client station is entering powersave mode, in an embodiment. Subsequently, when the bandwidth-limitedclient station 154 completes transmission to the new component channel,the bandwidth-limited client station 154 informs the AP 114 that theclient station is entering active mode. Accordingly, in an embodiment,the AP 114 will not transmit to the bandwidth-limited client station 154in a new component channel until the bandwidth-limited client station154 is ready for receiving in the new component channel. Power save modeoperation of the bandwidth-limited client station 154 during the timeperiod when the bandwidth-limited client station 154 is switchingchannels ensures that data units transmitted to the bandwidth-limitedclient station 154 will not be lost because the bandwidth-limited clientstation 154 is not ready to receive the data units in the new componentchannel, in an embodiment.

In some embodiments, the AP 114 and the client stations 154 arepermitted to transmit data units in a non-primary channel of acommunication channel, wherein the data units do not overlap a primarychannel of the communication channel. In an embodiment, the AP 114 maydetermine that a non-primary channel in which a bandwidth-limited clientstation 154 is operating is idle and may transmit a data unit to thebandwidth-limited client station 154 in the non-primary channel even ifthe primary channel is busy, in an embodiment. Similarly, abandwidth-limited client station 154 may determine that a non-primarychannel in which the bandwidth-limited client station 154 is operatingis idle and may transmit a data unit to the AP 114 in the non-primarychannel even if the primary channel is busy, in an embodiment. Asanother example, the AP 114 may transmit an MU data unit to a pluralityof client stations 154 in one or more non-primary channels that aredetermined to be idle even if the primary channel is busy and/or prompta plurality of client stations 154 for MU transmission in one or morenon-primary channels that are determined to be idle even if the primarychannel is busy, in an embodiment.

FIG. 7 is a block diagram of a procedure 700 that a communication deviceis configured to implement to determine that one or more non-primarychannels of a communication channel 702 are idle even if a primarychannel of the communication channel 702 is busy, according to anembodiment. In an embodiment, the network interface 122 (e.g., partiallythe MAC processor 126 and partially the PHY processor 130) of the AP 114is configured to implement the procedure 700. For ease of explanation,the procedure 700 is described with reference to the AP 114 of FIG. 1 .In other embodiments, however, the procedure 700 is implemented by othersuitable communication devices. For example, the procedure 700 isimplemented by the network interface 162 (e.g., partially the MACprocessor 166 and partially the PHY processor 170) of the client station154-1 of FIG. 1 , in an embodiment.

According to the procedure 700, the AP 114 performs respectiveCCA/backoff procedures corresponding to multiple ones (e.g., some orall) of component channels of the communication channel 702. In theembodiment of FIG. 7 , the communication channel 702 includes fourcomponent channels 704, and the AP 114 is configured to performrespective CCA/backoff operations 708 corresponding to each the fourcomponent channels 704. In another embodiment, the AP 114 is configuredto perform respective CCA/backoff operations 708 corresponding to some(e.g., two or three) but not all of the four component channels 704. Inother embodiments, the communication channel 702 includes other suitablenumbers of component channels (e.g., two, three, five, six, seven,etc.), and the AP 114 is configured to perform CCA/backoff operations708 corresponding to multiple ones (e.g., some or all) of the othersuitable number of component channels.

In an embodiment, the respective CCA/backoff operations 708 includemaintaining respective NAV timers corresponding to respective ones ofmultiple component channels. The AP 114 is configured to set respectiveones of the multiple NAV timers based on data units detected in thecorresponding component channels, in an embodiment. Similarly, therespective CCA/backoff operations 708 include maintaining respectivebackoff timers corresponding to respective ones of the multiplecomponent channels, in an embodiment. The AP 114 is configured toperform respective backoff operations in the respective ones of themultiple component channels using the respective backoff timerscorresponding to the respective ones of the multiple component channels,in an embodiment.

The component channels 704 include a primary channel 704-1 andnon-primary channels 704-2, 704-3 and 704-4, in an embodiment. The AP114 is configured to perform CCA/backoff operations 708-1 correspondingto the primary channel 704-1, and to perform CCA/backoff operations708-2, 708-3, 708-4 corresponding, respectively, to the non-primarychannels 704-2, 704-3 and 704-4, in an embodiment. In an embodiment, theAP 114 is configured to transmit in one or more non-primary componentchannels 704-2, 704-3 and 704-4 determined to be idle by the respectiveCCA/backoff operations 708-2, 708-3, 708-4, even if the primary channel704-1 is determined to be busy by the CCA/backoff operations 708-1.Thus, for example, when the AP 114 has data to transmit to abandwidth-limited client station 154 that is operating in a non-primarychannel (e.g., the non-primary channel 704-2), the AP 114 is configuredto transmit the data in the non-primary channel 704-2 if the AP 114determines based on the CCA/backoff operations 708-2 corresponding tothe non-primary channel 704-2 that the non-primary channel 704-2 is idleeven if the CCA/backoff operations 708-1 indicate that the primarychannel 704-1 is busy, in an embodiment.

FIG. 8 is a block diagram of a procedure 800 that a communication deviceis configured to implement to determine that one or more non-primarychannels of a communication channel 702 are idle even if a primarychannel of the communication channel 702 is busy, according to anotherembodiment. In an embodiment, the network interface 122 (e.g., partiallythe MAC processor 126 and partially the PHY processor 130) of the AP 114is configured to implement the procedure 800. For ease of explanation,the procedure 800 is described with reference to the AP 114 of FIG. 1 .In other embodiments, however, the procedure 800 is implemented by othersuitable communication devices. For example, the procedure 800 isimplemented by the network interface 162 (e.g., partially the MACprocessor 166 and partially the PHY processor 170) of the client station154-1 of FIG. 1 , in an embodiment.

In an embodiment, according to the procedure 800, the AP 114 performsCCA/backoff operations 808 corresponding to a single component channel704 at any given time, and the AP 114 performs the CCA/backoffoperations 808 in different component channels 704 at different times.For example, in an embodiment, the AP 114 performs first CCA/backoffoperations 808-1 corresponding to a first component channel 704, such asthe primary channel 704-1. The first CCA/backoff operations 808-1include determining whether first component channel 704 is idle or busy,in an embodiment. Additionally, the first CCA/backoff operations 808-1include determining whether one or more other component channels 704 areidle and available for transmission along with the first componentchannel 704, in an embodiment. When the AP 114 determines that the firstcomponent channel 704 is idle and one or more other component channels704 (if any) are idle and available for transmission along with thefirst component channel 704, the AP 114 transmits in the componentchannel 704-1 and the one or more other component channels (if any) thatare determined to be idle based on the first CCA/backoff operations808-1. After performing first CCA/backoff operations 808-1 correspondingto the first component channel 704, the AP 114 switches CCA/backoffoperations 808 to a second component channel 704, such a non-primarychannel 704-2, 704-3 or 704-4, and transmits in one or more componentchannel determined to be idle based on CCA/backoff operations 808-2performed in the second component channel, in an embodiment.

In an embodiment, the AP 114 performs the first CCA/backoff operations808-1 in connection with transmission during a first scheduled period(e.g., the SP 606-1 of FIG. 6 ) and switches the CCA/backoff operationsto perform the CCA/backoff operations 808-2 in connection withtransmission during a second scheduled period (e.g., the SP 606-1 ofFIG. 6 ). In another embodiment, the AP 114 performs the firstCCA/backoff operations 808-1 and the second CCA/backoff operations 808-2at different times during a same scheduled period, or performs the firstCCA/backoff operations 808-1 and the second CCA/backoff operations 808-2in connection with transmissions performed not during scheduled periods.

In an example embodiment, the CCA/backoff operations 808-1 correspondingto the primary channel 704-1 indicate that the primary channel 704-1 andthe non-primary component channels 704-2 and 704-4 are idle, but thenon-primary component channel 704-3 is busy. Accordingly, the AP 114transmits to one or more client stations 154 in the component channels704-1, 704-2 and 704-4 and/or prompts transmission by one or more clientstations 154 in the component channels 704-1, 704-2 and 704-4, in anembodiment. However, the AP 114 still has data to transmit in thecomponent channel 704-3, for example to a bandwidth-limited clientstation 154 that is operating in the component channel 704-3, and/or theAP 114 wishes to prompt a transmission in the component channel 704-3,for example by a bandwidth-limited client station 154 that is operatingin the component channel 704-3, in an embodiment. Accordingly, the AP114 (e.g., after or during transmission in the component channels 704-1,704-2 and 704-4) switches CCA/backoff operations 808 to the componentchannel 704-3, and performs to perform CCA/backoff operations 808-2corresponding to the component channel 704-3, in an embodiment. When theAP 114 determines based on the CCA/backoff operations 808-2 that thecomponent channel 704-3 is idle, the AP 114 transmits data to thebandwidth-limited client station 154 in the component channel 704-3,and/or prompts transmission by the bandwidth-limited client station 154in the component channel 704-3, even if the primary channel 704-1 atthat time is busy, in an embodiment.

In an embodiment, when the AP 114 switches CCA/backoff operations 808 toa new component channel (e.g., from the primary channel to a non-primarychannel or vice versa), the AP 114 senses the communication medium inthe new component channel for at least a predetermined delay timeperiod, such as a NAVSYNCDELAY time period. For example, upon switchingto the new component channel, the AP 114 initially sets its NAV to apredetermined value corresponding to the predetermined delay timeperiod. If the AP 114 does not detect any transmissions (e.g., dataunits) in the new component channel during the predetermined time period(e.g., when NAV reaches zero), the AP 114 initiates backoff in the newcomponent channel. On the other hand, if the AP 114 detects atransmission (e.g., a PHY data unit) in the new component channel duringthe during the predetermined time period (e.g., before NAV reacheszero), then the AP 114 resents its NAV based on the detected PHY dataunit, in an embodiment. For example, the AP 114 resets its NAV based onduration information in a header or a preamble of the PHY data unit. TheAP 114 then performs CCA/backoff operations using the reset NAV, in anembodiment. In an embodiment in which CCA/backoff operations areperformed in connection with transmission during a scheduled period, atleast a portion of the CCA/backoff operations may be performed outsideof the scheduled period. For example, the AP 114 is configured toperform at least a portion of sensing a communication medium whilecounting down a NAV timer (e.g., at least a portion of the NAVSYNCDELAYtime period) during a time period immediately preceding the scheduledperiod, in an embodiment.

In an embodiment, switching CCA/backoff operations 808 to a newcomponent channel (e.g., from the primary channel to a non-primarychannel or vice versa) includes determining backoff parameters (e.g., CWvalue, backoff timer value) to be utilized for performing backoffoperations in the new component channel. In an embodiment, when the AP114 switches CCA/backoff operations 808 to a new component channel, theAP 114 randomly or pseudorandomly chooses an initial value for thebackoff timer from the range of initial values [0, CW], where CWminvalue is used for CW. In another embodiment, switching CCA/backoffoperations 808 to a new component channel includes maintaining thebackoff parameters used in the previous component channel. Thus, forexample, after switching CCA/backoff operations 808 from the primarychannel 704-1 to the non-primary channel 704-3, the AP 114 maintains thebackoff parameters (e.g., CW value, backoff timer value) that wereutilized in the primary channel 704-1 for performing backoff operationsin the non-primary component channel 704-3, in an embodiment. In yetanother embodiment, switching CCA/backoff operations 808 to a newcomponent channel includes resuming CCA/backoff operations using thebackoff parameters that were used in the new component channel when theCCA/backoff operations were last performed in the new component channel.For example, in an embodiment, a memory (e.g., one or more registers,one or more locations in a memory device (e.g., a random access memory(RAM), a flash memory, etc.) is used to store backoff parameters lastused in respective ones of the component channels 704, and when the AP114 switches to a new component channel 704 the AP 114 resumes backoffoperation in the new component channel 704 using the backoff parametersstored in the memory for the new component channel 704, in anembodiment.

FIG. 9 is a flow diagram of an example method 900 for operation of afirst communication device in a communication channel that includesmultiple component channels, according to an embodiment. In anembodiment, the network interface 122 of the AP 114 of FIG. 1 isconfigured to implement the method 900. The method 900 is described inthe context of the AP 114 merely for explanatory purposes and, in otherembodiments, the method 900 is implemented by other suitablecommunication devices. For example, the network interface 122 of the AP114 of FIG. 1 is configured to implement the method 800, in anotherembodiment.

At block 902, respective frequency portions of the communication channelare allocated to respective ones of a plurality of second communicationdevices. For example, the AP 114 allocates respective frequency portionsof the communication channel to a plurality of client stations 154, inan embodiment. In an embodiment, the plurality of second communicationdevices includes a bandwidth-limited second communication device that iscapable of operating with a maximum bandwidth that is less than a fullbandwidth of the communication channel. For example, the plurality ofclient stations 154 includes a bandwidth-limited client station 154 thatis capable of operating with a maximum bandwidth that is less than afull bandwidth of the communication channel, in an embodiment. In anembodiment, the bandwidth-limited second communication device isoperating in a particular component channel of the plurality ofcomponent channels. For example, the bandwidth-limited secondcommunication device is operating in a particular non-primary componentchannel of the communication channel as previously negotiated betweenthe first communication device and the bandwidth-limited secondcommunication device, in an embodiment. In another embodiment, thebandwidth-limited second communication device is operating in a primarycomponent channel of the communication channel.

In an embodiment, allocating the respective frequency portions at block902 includes allocating a frequency portion to the bandwidth-limitedsecond communication device, wherein allocation of the frequency portionto the bandwidth-limited second communication device is restricted tothe particular component channel in which the second communicationdevice is operating. For example, in an embodiment in which thebandwidth-limited second communication device is operating in aparticular (e.g., previously negotiated) non-primary channel of thecommunication channel, allocation of the frequency portion to thebandwidth-limited second communication device is restricted to theparticular non-primary component channel of the communication channel.Thus, for example, the first communication device restricts allocationof the frequency portion to the bandwidth-limited second communicationdevice to allocation of one or more RUs in the particular non-primarycomponent channel, in an embodiment. As another example, in anembodiment in which the bandwidth-limited second communication device isoperating in a primary component channel, allocation of the frequencyportion to the bandwidth-limited second communication device isrestricted to the primary component channel of the communicationchannel. Thus, for example, the first communication device restrictsallocation of the frequency portion to the bandwidth-limited secondcommunication device to allocation of one or more RUs in the primarycomponent channel of the communication channel, in an embodiment.

At block 902, a first data unit is transmitted from the firstcommunication device to the plurality of second communication devices.In an embodiment, the data unit includes one or both of i) respectivedata for ones of the plurality of second communication devices in therespective frequency portions allocated to the respective ones of theplurality of second communication devices and ii) one or more triggerframes to prompt transmission of respective data by ones of theplurality of second communication devices in the respective frequencyportions allocated to the respective ones of the plurality of secondcommunication devices. For example, the data unit 302 of FIG. 3 istransmitted from the first communication device to the plurality ofsecond communication devices, in an embodiment. As another example, thedata unit 402 of FIG. 4 is transmitted from the first communicationdevice to the plurality of second communication devices, in anotherembodiment. As yet another example, the data unit 502 of FIG. 5 istransmitted from the first communication device to the plurality ofsecond communication devices, in yet another embodiment. In anotherembodiment, another suitable data unit is transmitted from the firstcommunication device to the plurality of second communication devices.

In an embodiment, a method includes allocating, at a first communicationdevice to a plurality of second communication devices, respectiveportions of a communication channel that includes a plurality ofcomponent channels including i) at least one primary component channeland ii) one or more non-primary component channels, wherein theplurality of second communication devices includes a bandwidth-limitedsecond communication device configured to operate with a maximumbandwidth that is less than a full bandwidth of the communicationchannel, wherein the bandwidth-limited second communication device isoperating in a particular component channel of the plurality ofcomponent channels, and allocating the respective frequency portionsincludes allocating a frequency portion to the bandwidth-limited secondcommunication device, wherein allocation of the frequency portion to thebandwidth-limited second communication device is restricted to theparticular component channel in which the second bandwidth-limitedcommunication device is operating. The method also includestransmitting, with the first communication device, a first data unit tothe plurality of second communication devices, the first data unitincluding one or both of i) respective data for ones of the plurality ofsecond communication devices in the respective frequency portionsallocated to the respective ones of the plurality of secondcommunication devices and ii) one or more trigger frames to prompttransmission of respective data by ones of the plurality of secondcommunication devices in the respective frequency portions allocated tothe respective ones of the plurality of second communication devices.

In other embodiments, the method comprises one of, or any suitablecombination of two or more of, the following features.

The particular component channel is a particular non-primary componentchannel of the communication channel.

The one or more trigger frames comprise a trigger frame that isduplicated in each component channel of the plurality of componentchannels of the communication channel to allow the bandwidth-limitedsecond communication device to receive the trigger frame in theparticular non-primary component channel of the communication channel.

The particular component channel is previously negotiated between thefirst communication device and the bandwidth-limited secondcommunication device.

The particular component channel previously negotiated between the firstcommunication device and the bandwidth-limited second communicationdevice is negotiated for operating during one or more scheduled timeperiods.

The method further comprises transmitting, with the first communicationdevice at a time outside the one or more scheduled time periods, asecond data unit that includes data for the bandwidth-limited secondcommunication device in a primary component channel of the componentchannel.

The method further comprises generating, with the first communicationdevice, a management frame for transmission in the communicationchannel, wherein the management frame is duplicated in each of theplurality of component channels of the communication channel, andtransmitting, with the first communication device, the management frameduplicated in each of the plurality of component channels of thecommunication channel to allow the bandwidth-limited secondcommunication device operating in a non-primary component channel of thecommunication channel to receive the management frame in the non-primarycomponent channel.

The management frame is a beacon frame.

The method further comprises, prior to transmitting the first data unit,performing, at the first communication device, respective backoffprocedures corresponding to multiple ones the component channels todetermine whether respective ones of the multiple component channels areidle, and transmitting the first data unit comprises transmitting thefirst data unit only in component channels that are determined to beidle based on the respective backoff procedures performed in themultiple ones of the component channels.

The method further comprises: prior to transmitting the first data unit,performing, at the first communication device, a first backoff procedurecorresponding to a first component channel to determine whether one ormore component channels of the plurality of component channels are idle;transmitting the first data unit i) only if the first component channelis determined to be idle and ii) only in the one or more componentchannels determined to be idle based on the first backoff procedure;subsequent to the first backoff procedure, performing, at the firstcommunication device, a second backoff procedure corresponding to asecond component channel of the plurality of component channels, thesecond component channel being a component channel other than the firstcomponent channel; and transmitting, with the first communication deviceto one or more of the second communication devices, a second data unitin the one or more component channels determined to be idle based on thesecond backoff procedure.

Performing the second backoff procedure corresponding to the secondcommunication channel comprises performing the second backoff procedureusing one of i) backoff parameters carried over from the first backoffprocedure corresponding to the first component channel, ii) backoffparameters resumed from a backoff procedure previously performedcorresponding to the second communication channel, and iii) newlyselected backoff parameters for performing the second backoff procedurecorresponding to the second communication channel.

In another embodiment, an apparatus comprises a first network interfacedevice associated with a first communication device, wherein the firstnetwork interface device comprises one or more integrated circuit (IC)devices configured to allocate, to a plurality of second communicationdevices, respective portions of a communication channel that includes aplurality of component channels including i) at least one primarycomponent channel and ii) one or more non-primary component channels,wherein the plurality of second communication devices includes abandwidth-limited second communication device configured to operate witha maximum bandwidth that is less than a full bandwidth of thecommunication channel, wherein the bandwidth-limited secondcommunication device is operating in a particular component channel ofthe plurality of component channels, and allocating the respectivefrequency portions includes allocating a frequency portion to thebandwidth-limited second communication device, wherein allocation of thefrequency portion to the bandwidth-limited second communication deviceis restricted to the particular component channel in which thebandwidth-limited second communication device is operating. The one ormore IC devices are also configured to transmit a first data unit to theplurality of second communication devices, the first data unit includingone or both of i) respective data for ones of the plurality of secondcommunication devices in the respective frequency portions allocated tothe respective ones of the plurality of second communication devices andii) one or more trigger frames to prompt transmission of respective databy ones of the plurality of second communication devices in therespective frequency portions allocated to the respective ones of theplurality of second communication devices.

In other embodiments, the apparatus comprises one of, or any suitablecombination of two or more of, the following features.

The particular component channel is a particular non-primary componentchannel of the communication channel.

The one or more trigger frames comprise a trigger frame that isduplicated in each component channel of the plurality of componentchannels of the communication channel to allow the bandwidth-limitedsecond communication device to receive the trigger frame in theparticular non-primary component channel of the communication channel.

The particular component channel is previously negotiated between thefirst communication device and the bandwidth-limited secondcommunication device.

The particular component channel previously negotiated between the firstcommunication device and the bandwidth-limited second communicationdevice is negotiated for operating during one or more scheduled timeperiods, and the one or more IC devices are further configured totransmit, at a time outside the one or more scheduled time periods, asecond data unit that includes data for the bandwidth-limited secondcommunication device in a primary component channel of the componentchannel.

The one or more IC devices are further configured to: generate amanagement frame for transmission in the communication channel, whereinthe management frame is duplicated in each of the plurality of componentchannels of the communication channel, and transmit the management frameduplicated in each of the plurality of component channels of thecommunication channel to allow the bandwidth-limited secondcommunication device operating in a non-primary component channel of thecommunication channel to receive the management frame in the non-primarycomponent channel.

The management frame is a beacon frame.

The one or more IC devices are further configured to: prior totransmitting the first data unit, perform respective backoff procedurescorresponding to multiple ones the component channels to determinewhether respective ones of the multiple component channels are idle, andtransmit the first data unit only in component channels that aredetermined to be idle based on the respective backoff proceduresperformed in the multiple ones of the component channels.

The one or more IC devices are further configured to: prior totransmitting the first data unit, perform a first backoff procedurecorresponding to a first component channel to determine whether one ormore component channels of the plurality of component channels are idle,transmit the first data unit i) only if the first component channel isdetermined to be idle and ii) only in the one or more component channelsdetermined to be idle based on the first backoff procedure, subsequentto the first backoff procedure, perform a second backoff procedurecorresponding to a second component channel of the plurality ofcomponent channels, the second component channel being a componentchannel other than the first component channel, and transmit, to one ormore of the second communication devices, a second data unit in the oneor more component channels determined to be idle based on the secondbackoff procedure.

Performing the second backoff procedure corresponding to the secondcommunication channel comprises performing the second backoff procedureusing one of i) backoff parameters carried over from the first backoffprocedure corresponding to the first component channel, ii) backoffparameters resumed from a backoff procedure previously performedcorresponding to the second communication channel, and iii) newlyselected backoff parameters for performing the second backoff procedurecorresponding to the second communication channel.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented utilizing hardware, a processorexecuting firmware instructions, a processor executing softwareinstructions, or any combination thereof. When implemented utilizing aprocessor executing software or firmware instructions, the software orfirmware instructions may be stored in any computer readable memory suchas on a magnetic disk, an optical disk, or other storage medium, in aRAM or ROM or flash memory, processor, hard disk drive, optical diskdrive, tape drive, etc. The software or firmware instructions mayinclude machine readable instructions that, when executed by one or moreprocessors, cause the one or more processors to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), a programmable logic device (PLD), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method for communicating in a wireless localarea network (WLAN) that utilizes a communication channel having aplurality of component channels, the plurality of component channelsincluding i) at least one primary component channel in which an accesspoint transmits management frames including beacon frames, and ii) oneor more non-primary component channels, the method comprising:receiving, at a bandwidth-limited client station that is configured tooperate with a maximum bandwidth that is less than a full bandwidth ofthe communication channel, target wake time (TWT) information from theaccess point, the TWT information regarding a TWT period with the accesspoint and including an indication of a particular non-primary componentchannel among the one or more non-primary component channels in whichthe bandwidth-limited client station is expected to operate during theTWT period; switching operation of the bandwidth-limited client stationfrom one of the at least one primary component channels to theparticular non-primary component channel in connection with a start ofthe TWT period; operating the bandwidth-limited client station in theparticular non-primary component channel during the TWT period;receiving, at the bandwidth-limited client station during the TWTperiod, a data unit from the access point via the particular non-primarycomponent channel; receiving, at the bandwidth-limited client station, afirst legacy packet from the access point in the particular non-primarycomponent channel, the first legacy packet including a beacon frame;receiving, at the bandwidth-limited client station, a trigger frame fromthe access point in a second legacy packet in the particular non-primarycomponent channel during the TWT period, the trigger frame configured toprompt the bandwidth-limited client station to transmit an uplinktransmission in the particular non-primary component channel; and inresponse to the trigger frame, transmitting, by the bandwidth-limitedclient station, the uplink transmission in the particular non-primarycomponent channel.
 2. The method of claim 1, further comprising:measuring, at the bandwidth-limited client station, a predetermineddelay time period corresponding to the start of the TWT period; and nottransmitting the uplink transmission in response to determining that thedelay time period has not expired; wherein transmitting the uplinktransmission in response to the trigger frame comprises transmitting theuplink transmission further in response to determining that the delaytime period has expired.
 3. The method of claim 1, further comprising:performing, at the bandwidth-limited client station, a backoff operationduring the TWT period and prior to transmitting the uplink transmissionin response to the trigger frame; not transmitting the uplinktransmission in response to the trigger frame in response to the backoffoperation indicating that the particular non-primary component channelis not clear for transmission; wherein transmitting the uplinktransmission in response to the trigger frame comprises transmitting theuplink transmission further in response to the backoff operationindicating that the particular non-primary component channel is clearfor transmission.
 4. The method of claim 1, wherein receiving the TWTinformation comprises: receiving the TWT information via the primarychannel while the bandwidth-limited client station is operating in theprimary component channel.
 5. The method of claim 4, further comprising:transmitting, by the bandwidth-limited client station, a request toestablish a TWT session via the primary component channel, wherein therequest corresponds to establishing a TWT session with the access pointand is configured to prompt the access point to transmit the TWTinformation.
 6. A wireless communication device for communicating in awireless local area network (WLAN) that utilizes a communication channelhaving a plurality of component channels, the plurality of componentchannels including i) at least one primary component channel in which anaccess point transmits management frames including beacon frames, andii) one or more non-primary component channels, the wirelesscommunication device comprising: a wireless network interface devicethat is configured to operate with a maximum bandwidth that is less thana full bandwidth of the communication channel, wherein the wirelessnetwork interface device comprises one or more integrated circuit (IC)devices configured to: receive target wake time (TWT) information fromthe access point, the TWT information regarding a TWT period with theaccess point and including an indication of a particular non-primarycomponent channel among the one or more non-primary component channelsin which the wireless communication device is expected to operate duringthe TWT period, switch operation of the wireless network interfacedevice from one of the at least one primary component channels to theparticular non-primary component channel in connection with a start ofthe TWT period, operate the wireless network interface device in theparticular non-primary component channel during the TWT period, receive,during the TWT period, a data unit from the access point via theparticular non-primary component channel, receive a first legacy packetfrom the access point in the particular non-primary component channel,the first legacy packet including a beacon frame, receive a triggerframe from the access point in a second legacy packet in the particularnon-primary component channel during the TWT period, the trigger frameconfigured to prompt the wireless communication device to transmit anuplink transmission in the particular non-primary component channel, andcontrol the wireless network interface device to, in response to thetrigger frame, transmit the uplink transmission in the particularnon-primary component channel.
 7. The wireless communication device ofclaim 6, wherein: the wireless network interface device comprises atimer implemented on the one or more IC devices; the one or more ICdevices are further configured to: measure a predetermined delay timeperiod corresponding to the start of the TWT period with the timer, nottransmit the uplink transmission in response to the trigger frame inresponse to determining that the delay time period has not expired, andtransmit the uplink transmission further in response to determining thatthe delay time period has expired.
 8. The wireless communication deviceof claim 6, wherein the one or more IC devices are further configuredto: perform a backoff operation during the TWT period and prior totransmitting the uplink transmission in response to the trigger frame;not transmit the uplink transmission in response to the backoffoperation indicating that the particular non-primary component channelis not clear for transmission; and transmit the uplink transmissionfurther in response to the backoff operation indicating that theparticular non-primary component channel is clear for transmission. 9.The wireless communication device of claim 6, wherein the one or more ICdevices are configured to: receive the TWT information via the primarychannel while the wireless network interface device is operating in theprimary component channel.
 10. The wireless communication device ofclaim 9, wherein the one or more IC devices are further configured to:transmit a request to establish a TWT session via the primary componentchannel, wherein the request corresponds to establishing a TWT sessionwith the access point and is configured to prompt the access point totransmit the TWT information.
 11. The wireless communication device ofclaim 6, wherein the wireless network interface device furthercomprises: one or more wireless transceivers implemented at leastpartially on the one or more IC devices.
 12. The wireless communicationdevice of claim 11, further comprising: one or more antennas coupled tothe one or more wireless transceivers.
 13. The wireless communicationdevice of claim 6, wherein the wireless network interface device furthercomprises: a physical layer (PHY) processor implemented on the one ormore IC devices the PHY processor configured to: extract one or more MACprotocol data units (MPDUs) from one or more PHY protocol data units(PPDUs) received from the access point via the particular non-primarycomponent channel during the TWT period, and extract the beacon framefrom the legacy packet received from the access point in the particularnon-primary component channel; and a media access control (MAC)processor implemented on the one or more IC devices and coupled to thePHY processor, the MAC processor configured to: receive the one or moreMPDUs from the PHY processor, process the one or more MPDUs received,receive the beacon frame from the PHY processor, and process the beaconframe.